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Matt,<BR>
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please find the log_summary attached.<BR>
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Michele<BR>
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On Sat, 2015-07-18 at 21:56 -0500, Matthew Knepley wrote:
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On Sat, Jul 18, 2015 at 9:53 PM, Michele Rosso <<A HREF="mailto:mrosso@uci.edu">mrosso@uci.edu</A>> wrote:
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Barry,<BR>
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I tried the master branch of PETSc as you suggested and unfortunately the problem with KSP being set to GMRES on the coarse level when using "-mg_coarse_ksp_type preonly" is still there. I attached the output from ksp view and the options stack.<BR>
Am I missing something?<BR>
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If you show output from -log_summary we can make sure you are running the version we expect.
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Thanks,
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Matt
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Thanks,<BR>
Michele<BR>
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On Thu, 2015-07-16 at 17:30 -0500, Barry Smith wrote:
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Michel,
This is a very annoying feature that has been fixed in master <A HREF="http://www.mcs.anl.gov/petsc/developers/index.html">http://www.mcs.anl.gov/petsc/developers/index.html</A> I would like to have changed it in maint but Jed would have a shit-fit :-) since it changes behavior.
Barry
<FONT COLOR="#737373">> On Jul 16, 2015, at 4:53 PM, Michele Rosso <<A HREF="mailto:mrosso@uci.edu">mrosso@uci.edu</A>> wrote:</FONT>
<FONT COLOR="#737373">> </FONT>
<FONT COLOR="#737373">> Hi,</FONT>
<FONT COLOR="#737373">> </FONT>
<FONT COLOR="#737373">> I am performing a series of solves inside a loop. The matrix for each solve changes but not enough to justify a rebuilt of the PC at each solve.</FONT>
<FONT COLOR="#737373">> Therefore I am using KSPSetReusePreconditioner to avoid rebuilding unless necessary. The solver is CG + MG with a custom PC at the coarse level.</FONT>
<FONT COLOR="#737373">> If KSP is not updated each time, everything works as it is supposed to. </FONT>
<FONT COLOR="#737373">> When instead I allow the default PETSc behavior, i.e. updating PC every time the matrix changes, the coarse level KSP , initially set to PREONLY, is changed into GMRES </FONT>
<FONT COLOR="#737373">> after the first solve. I am not sure where the problem lies (my PC or PETSc), so I would like to have your opinion on this.</FONT>
<FONT COLOR="#737373">> I attached the ksp_view for the 2 successive solve and the options stack.</FONT>
<FONT COLOR="#737373">> </FONT>
<FONT COLOR="#737373">> Thanks for your help,</FONT>
<FONT COLOR="#737373">> Michel</FONT>
<FONT COLOR="#737373">> </FONT>
<FONT COLOR="#737373">> </FONT>
<FONT COLOR="#737373">> </FONT>
<FONT COLOR="#737373">> <ksp_view.txt><petsc_options.txt></FONT>
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--
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What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<BR>
-- Norbert Wiener
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